1. Field of the Invention
The present invention relates to substrates having a pattern such as an insulating film, a conductive film, and a semiconductor film that are formed with the use of a screen printing method and to a method for manufacturing thereof. The present invention also relates to a semiconductor device having a film pattern that is formed by a screen printing method and a method for manufacturing thereof.
2. Description of the Related Art
The screen printing method is such a method that, as shown in FIG. 2B, a screen printing plate 100 in which a frame 103 is provided with a wire netting (mesh) 104 and an emulsion 105 for a mask is provided above a substrate 101, and, as shown in FIG. 2A, composition 106 is provided over the screen printing plate and extruded while pushing out with the use of a squeegee 107, a roller, or the like to be applied to the surface of the substrate 101. FIG. 2B shows a perspective view of the substrate provided with the screen printing plate, and FIG. 2A shows a cross-sectional view taken along A-B thereof.
Then, as shown in FIG. 2C, a composition 111 applied over the substrate 101 is dried and baked to form a film pattern 131 as shown in FIGS. 2D and 2E.
The screen printing method has advantages in the production cost and the throughput because the screen printing method needs few number of steps and devices and the method for manufacturing is comparatively simple and easy. Therefore, the screen printing method is adopted in forming steps of a wiring provided over the substrate, a partition wall (bank) and a pixel electrode provided in a plasma display panel and a light-emitting display device, and a solder bump and a package covering semiconductor elements such as IC and LSI, and the like.
However, in the case of printing a composition over the substrate with the use of the screen printing method, the applied composition that fills in mesh opening portions are connected to each other to be a liner composition. Therefore, as a top view shown in FIG. 2E, a composition having a curved (undulant) shape on the side surfaces thereof, which is different from the shape of the mask, are formed at a region 132 of the composition that is applied to fill opening portions and a region 133 of the composition connected thereto. Accordingly, distances 134 between the adjacent film patterns 131 are different. In addition, surfaces of the composition have different film thicknesses corresponding to the opening portions of the mask, and the surfaces are uneven.
A film pattern formed by baking the paste in such a shape has also different distances between adjacent film patterns. In addition, the surface is uneven.
When an antenna such as a wireless chip (also referred to as an ID tag, an IC tag, and IC chip, an RF (Radio Frequency) tag, a wireless tag, an electronic tag, or an RFID (Radio Frequency Identification)) that can receive and transmit data wirelessly by using the above film pattern is formed, the inductance in the antenna changes and resonant frequency decreases thereby reducing electromotive force. In addition, short circuit occurs easily with adjacent antennas.
In the region 133 with a narrow line width of the composition, the composition is easily separated, which results in reduced yield. In addition, depending on the viscosity of the composition, the film thickness of the conductive film becomes thinner. The composition may be printed several times in order to avoid such problems. However, in this case, the number of steps increases and adjacent compositions are, connected to each other.